Balanced Photo-Detector
The external page Electronics Lab of the Department of Physics in Basel presents a external page Balanced Photo-Detector (SP 1023) that combines low noise and with high bandwidth. This combination is important for optical measurements. Commercial available photo-detecots may not have an exchangable photo-diode and can not provide the bandwith with the low noise properties in one device.
This Balanced Photo-Detector (BPD) combines large bandwidth (50 MHz) with low noise performance. At 1 MHz the typical dark noise density is only 1.7 pA/sqrt(Hz). At a wavelength of 800 nm this corresponds to an optical power noise density of 3.2 pW/sqrt(Hz). At an optical power of 8.3 μW (@800 nm) on both photodiodes, the shot-noise density reaches to the dark noise density.
The device is equipped with two large-area (d = 0.8 mm) silicon PIN-photodiodes (Hamamatsu S5972). Those cover an optical wavelength range from 320 nm to 1 μm. At 800 nm these photodiodes have a quantum-efficiency of around 84%. Since the photodiodes are mounted on sockets they can be changed easily. They can also be replaced by other low-capacitance photodiodes, covering different wavelength ranges.
The BPD has a gain of 1E4 V/A and the broadband output signal drives up to ±3.5 V when terminated with 50 Ohm. Several monitor signals (I-PD+, I-PD-, I-PD Diff) are available for DC-readout or slow-control; they are also very handy when setting up and adjusting an optical experiment.
Specifications
• Optical power difference on two photodiodes
• Large bandwidth (-3 dB): 50 MHz
• Low dark noise (equivalent 800 nm optical power):@1 MHz: 1.7 pA/√Hz (3.2 pW/√Hz)
@10 MHz: 5.1 pA/√Hz (9.5 pW/√Hz)
• High differential signal gain: 104 V/A
• Wavelength range: 320 nm to 1’000 nm
• Two large-area (d=0.8 mm) Si-PIN photodiodes Hamamatsu S5972 (84% QE @800 nm)
• Broadband signal output [10 V/mA]: ± 3.5 V @50 Ω
• Low gain [1 V/mA] monitor signals output: ±10 V
• Up to 5 mA current per photodiode
• Electrically insulated mountable on an optical table
• Small size: L = 93 mm, W = 55 mm, h = 42 mm
• Low weight: 135 g
• ±15 V Floating Power Supply (SP 874) included
• BNC adapter for monitor signals included
Data sheet SP 1023: Download Version 1.3 (PDF, 777 KB)
Available in small batch series. Price for QSIT affiliates: 980 CHF.
To order, please contact the developer of SP 1023,
